Allow `WithUrl` to reference an endpoint without breaking the fluent chain

[afscrome]

Is there an existing issue for this?

• I have searched the existing issues

Is your feature request related to a problem? Please describe the problem.

Right now if you want to add a custom url referencing an endpoint, you have to break the fluent chain

var resource = builder.AddContainer("redis", "redis")
    .WithHttpEndpoint(targetPort: 8080);

resource.WithUrl($"{resource.GetEndpoint("http")}/swagger", "Swagger");

Describe the solution you'd like

For this specific case, it would be really nice if you could handle this without having to break the chain

   builder.AddContainer("redis", "redis")
         .WithHttpEndpoint(targetPort: 8080)
         .WithUrl("http", "/swagger", "Swagger");

(This suggestion suggestion would likely require #8636 to work)

That said, there is a more general problem here that a number of APIs have (e.g. try to add a url to an environment variable). So you could argue for a more general solution, rather than adding more WithUrl overloads. But given that urls are closely linked with endpoints, I don't see too many problems having special handling for endpoints in WithUrl here.

Additional context

The only gotcha I'd think about in scope for 9.2 is that if we did want to implement the api suggested above, there will be a conflict between:

// Existing method
WithUrl(string url, string ? displayText = null)
// New method
WithUrl(string endpoint, string url, string ? displayText = null)

Which would need a breaking change to resolve. So it could be worth doing something now that avoids a breaking change later.

(To be clear, I'm not strongly pushing for this to be done in 9.2, I just think it's worth thinking about)

cc @DamianEdwards

[afscrome]

Note, using WithUrl over WithUrlForEndpoint differs by allows you to add an additional url, rather than replace the existing one

[DamianEdwards]

I think perhaps we could add an overload of WithUrlForEndpoint that accepts an enum describing the behavior as either replace or add (similar to the annotation add methods), as more overloads of WithUrl with string parameters is unwieldy.

[DamianEdwards]

Closed in #8743